The study will proceed along two lines. I. Parotid gland. Slices will be tested for the presence of receptors for various hormones and neurotransmitters not hitherto known to act on the parotid gland (i.e., vasoactive intestinal peptide). Because of the extensive information on the response of the parotid acinar cell to alpha and beta-adrenergic agents and to muscarinic agents, the response to other hormones and neurotransmitters could be readily checked and characterized. II. Beta-Adrenergic receptor. The mechanism of action of this receptor (which in the parotid gland activates enzyme secretion) will be studied at the molecular level using mainly preparations of turkey erythrocyte membranes. The receptor will be transferred to the adenylate cyclase in other membranes by a new membrane fusion procedure which is at the final stages of development. Competition between the transferred receptor and the indigenous receptor (PGE1) will be studied. Dependence of receptor transfer on additional membrane components will also be investigated.